CN114207287B

CN114207287B - Blower fan

Info

Publication number: CN114207287B
Application number: CN202180003259.XA
Authority: CN
Inventors: 坂田和夫; 奥野薫; 木下龙男
Original assignee: Osaka Forced Draft Fan Manufacturing Co ltd
Current assignee: Osaka Forced Draft Fan Manufacturing Co ltd
Priority date: 2020-06-04
Filing date: 2021-03-23
Publication date: 2024-05-14
Anticipated expiration: 2041-03-23
Also published as: CN114207287A; JPWO2021246029A1; KR102653737B1; KR20210151860A; WO2021246029A1; JP7319636B2

Abstract

A blower is provided with: a rotary shaft (21) inserted into a shaft hole (12) of a housing (10) in which a gas passage (11) is formed, an impeller (22) supported by the rotary shaft (21), and a sealing device (30) for sealing the shaft hole (12), the sealing device (30) comprising: a first seal ring (31) and a second seal ring (32) that surround the rotary shaft (21) in the vicinity of the shaft hole (12); a shaft seal case (33) surrounding the first seal ring (31) and the second seal ring (32); a static pressure gas seal unit (40) that forms a main seal chamber (42) in which seal air higher than the pressure in the gas passage (11) is introduced in the shaft seal box (33) so as to prevent leakage of exhaust gas from the gas passage (11) to the atmosphere; and a backup seal unit (60) that has an annular third seal ring (61) surrounding the rotary shaft (21) on the outer side in the axial direction relative to the shaft seal case (33), and that forms an auxiliary seal chamber (62) that restricts leakage of seal air from the atmosphere side of the main seal chamber (42).

Description

Blower fan

Technical Field

The present invention relates to blowers, and more particularly to blowers suitable for use in exhaust gas recirculation systems of large engines.

Background

As a blower that sucks and boosts a gas to be blown, there has been conventionally known a blower that: a recirculation blower that boosts and recirculates exhaust gas discharged from a power-outputting or power-outputting system to the system, an auxiliary blower that boosts supply gas (including low-pressure recirculation gas) supplied to the system, and the like.

For example, as one of exhaust emission reduction technologies of an engine such as a marine diesel engine, an EGR system (exhaust gas recirculation system) has been widely used in which a part of exhaust gas of the engine is recirculated to an intake side (an intake side in the case of scavenging) of the engine to reduce NOx (nitrogen oxides) in the exhaust gas, and in such an EGR system, an EGR blower that boosts a part of the exhaust gas to a pressure capable of recirculation is described in, for example, patent documents 1 and 2.

Further, for example, patent document 3 describes the following blower: the flow rate of the recirculated exhaust gas can be controlled according to the blower rotational speed itself, and a rotation sensor that measures the blower rotational speed is mounted.

Patent document 4 describes a centrifugal blower in which an impeller and a rotary shaft are integrally molded with each other by a resin material and housed in a casing, and first and second seal rings made of a fluorine-based resin are provided at a plurality of positions in the casing in the axial direction of the rotary shaft, the first and second seal rings having inner peripheral surfaces having substantially the same diameter as the outer peripheral surface of the rotary shaft, and seal air being supplied into a casing internal space between the two seal rings.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2011-157959

Patent document 2: japanese patent application laid-open No. 2012-172647

Patent document 3: japanese patent laid-open No. 2002-332919

Patent document 4: japanese patent laid-open publication 2016-89671

Disclosure of Invention

Problems to be solved by the invention

However, in such a conventional blower as described above, if the pressure of the seal air supplied to the impeller-side space inside the casing is set to be sufficiently greater than the pressure inside the impeller housing in order to suppress intrusion of the EGR gas, which is boosted in the impeller housing and is to be recirculated to the engine, into the inner space side of the casing through the shaft hole of the impeller rotating shaft, there is a problem as follows: the amount of seal air leaking from the impeller-side space to the motor-side space side communicating with the outside (atmosphere side) of the casing increases.

Accordingly, the conventional blower has the following problems: a problem of an increase in power consumption of a driving motor driving the seal air supply source, or a problem of an EGR blower which is difficult to use for a marine engine provided in a ship, and the like.

The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a blower capable of suppressing power consumption of a seal air supply source, and to provide a blower suitable for an EGR blower of a marine engine.

Solution for solving the problem

(1) In order to achieve the above object, a blower according to the present invention includes: a housing formed with a gas passage and a shaft hole communicating with the gas passage; a rotation shaft rotatably inserted into the shaft hole of the housing; an impeller supported by the rotating shaft and housed in the housing; and a sealing device that seals the shaft hole, the blower being characterized in that the sealing device includes: a first seal ring and a second seal ring in the form of rings surrounding the rotary shaft in the vicinity of the shaft hole; an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner wall portions integrally joined to the annular wall portion on both sides in an axial direction of the rotary shaft; a static pressure gas seal unit that forms a main seal chamber in the shaft seal case so as to prevent leakage of the exhaust gas from the gas passage to the atmosphere, the main seal chamber being configured to introduce seal air having a pressure higher than that in the gas passage and to bring the first seal ring and the second seal ring into close contact with the pair of inner side wall portions; and a backup seal unit having an annular third seal ring that surrounds the rotary shaft on an axially outer side of the shaft seal box from the gas passage, and forming an auxiliary seal chamber that restricts leakage of seal air from the main seal chamber to an atmosphere side.

According to this configuration, in the present invention, the seal air having a pressure higher than the pressure in the gas passage is introduced into the main seal chamber formed between the first seal ring and the second seal ring by the static pressure gas seal unit, so that the exhaust gas in the blower can be reliably prevented from leaking from the gas passage side to the atmosphere side. In addition, when the front-rear pressure difference of the second seal ring is suppressed by the third seal ring of the backup seal unit, the front-rear pressure difference of the third seal ring is also suppressed, so that the leakage flow rate of seal air to the atmosphere corresponding to the front-rear pressure difference of each seal ring can be effectively suppressed and reduced.

(2) In a preferred embodiment of the present invention, the casing may be formed with the gas passage through which a part of the exhaust gas of the engine can be introduced, and the shaft hole may be in communication with the gas passage, and the impeller may recirculate the exhaust gas introduced into the gas passage and boosted in pressure to the engine.

In this case, the EGR blower is suitable for recirculating the exhaust gas of the engine in order to reduce NOx and the like.

(3) In a preferred embodiment of the present invention, at least the second seal ring on the atmosphere side of the first seal ring and the second seal ring may be configured by a plurality of arcuate segment seal members adjacent in the circumferential direction, the plurality of segment seal members having first facing surfaces and second facing surfaces, the first facing surfaces expanding in the axial direction and the radial direction and facing in the circumferential direction, and the second facing surfaces expanding in the circumferential direction and the radial direction and facing in the axial direction.

With this configuration, the shape of the minute gap between the plurality of segment seal members can be appropriately set according to the inner peripheral surface shape and the end shape of the segment seal members, and the flow rate of the seal air passing through the minute gap of the second seal ring and the front-rear pressure difference of the second seal ring can be stably ensured.

(4) In a preferred embodiment of the present invention, the backup seal unit may further include an outer annular member that covers the third seal ring from a radially outer side and an axially outer side with respect to the shaft seal case and isolated from the gas passage, and an elastic member that biases the third seal ring in the axial direction of the rotary shaft so that the third seal ring is in close contact with the outer annular member.

In this case, the auxiliary seal chamber can be easily formed by the third seal ring and the outer annular member, and the stable seal posture of the third seal ring can be set, so that leakage of seal air to the atmosphere during operation can be more effectively reduced.

(5) In a preferred embodiment of the present invention, the outer annular member may be fixed to an axially outer side of the shaft seal case, which is isolated from the gas passage.

With this configuration, the third seal ring and the outer annular member can be easily added to the conventional blower.

(6) In a preferred embodiment of the present invention, the blower may be provided with a motor for driving the rotation shaft to rotate, and the housing may be integrally connected to the motor.

In this case, a compact blower can be manufactured.

(7) In a preferred embodiment of the present invention, a circular plate-like throwing plate having a diameter larger than an inner peripheral diameter of the outer annular member may be disposed on the rotating shaft on the outer side in the axial direction than the outer annular member.

According to this configuration, the seal air leaking from the auxiliary seal chamber to the outside in the axial direction can be thrown off in the radiation outward direction together with surrounding dust or the like by the throwing-off plate, and intrusion of dust into the motor side can be effectively suppressed.

(8) In a preferred embodiment of the present invention, there is provided a sealing device for an EGR blower, the sealing device being attached to a blower and sealing a shaft hole, the sealing device comprising: a housing having a gas passage through which a part of exhaust gas of an engine can be introduced and the shaft hole communicating with the gas passage; a rotation shaft rotatably inserted into the shaft hole of the housing; and an impeller that is supported by the rotary shaft and housed in the casing, and that recirculates EGR gas introduced into the gas passage and boosted to the engine, a sealing device of the EGR blower including: a first seal ring and a second seal ring in the form of rings surrounding the rotary shaft in the vicinity of the shaft hole; an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner wall portions integrally joined to the annular wall portion on both sides in an axial direction of the rotary shaft; a static pressure gas seal unit that forms a main seal chamber in the shaft seal case so as to prevent leakage of the exhaust gas from the gas passage to the atmosphere, the main seal chamber being configured to introduce seal air having a pressure higher than that in the gas passage and to bring the first seal ring and the second seal ring into close contact with the pair of inner side wall portions; and a backup seal unit having an annular third seal ring that surrounds the rotary shaft on an axially outer side of the shaft seal box from the gas passage, and forming an auxiliary seal chamber that restricts leakage of seal air from the main seal chamber to an atmosphere side.

According to this configuration, leakage of the exhaust gas in the blower from the gas passage side to the atmosphere side in the ship can be effectively suppressed by the pressurized seal air of the static pressure gas seal unit, and the leakage amount of the seal air to the atmosphere side can be sufficiently reduced by cooperation of the static pressure gas seal unit and the backup seal unit.

Effects of the invention

According to the present invention, it is possible to provide a blower capable of suppressing power consumption of a seal air supply source, and to provide a blower suitable for an EGR blower of a marine engine.

Drawings

Fig. 1 is a schematic diagram of an EGR blower and an EGR system of a marine engine including the EGR blower according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view of a portion near a shaft hole of an EGR blower according to an embodiment of the present invention.

Fig. 3 is a partially enlarged sectional view showing the M portion of fig. 2 by a double-stippled coil in further enlargement.

Fig. 4A is a front view of a segmented seal ring in an EGR blower according to an embodiment of the present invention.

Fig. 4B is a block diagram of a seal ring of the sectional seal type in the EGR blower according to the embodiment of the present invention, and is a view in the direction B in fig. 4A.

Fig. 5 is an enlarged cross-sectional view of a portion near a shaft hole of an EGR blower according to another embodiment of the present invention.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

(One embodiment)

Fig. 1 to 4B show a case where a blower according to an embodiment of the present invention is provided as an EGR blower in a power system with an EGR device.

First, the constitution thereof will be described.

As shown in fig. 1, the power system 100 of the present embodiment includes an engine 110, a turbocharger 120, and an EGR device 130, wherein the engine 110 is a multi-cylinder large two-stroke diesel engine, and the engine 110, the turbocharger 120, and the EGR device 130 are mounted in a cabin of a ship, not shown.

The engine 110 is an electronically controlled high-output engine that can be used as a main engine of an ocean-going vessel, for example, and has the following structure: a fuel supply unit 102, an air supply receiver 103, an exhaust receiver 104, and the like are mounted on the multi-cylinder engine main body 101. In addition, although the present embodiment is for a ship, the engine 110 may be used as a stationary engine for operating a generator of a power plant, for example, in a case other than a ship.

A plurality of cylinders 111 are provided in the multi-cylinder engine main body 101. The plurality of cylinders 111 are connected to the supply air receiver 1033 via scavenging ports 113, respectively, and can exhaust air into the exhaust air receiver 104 when the corresponding exhaust valves 114 are opened. In each cylinder 111, when air that is sucked in by scavenging and compressed by the piston 112 to a point equal to or higher than the ignition point and fuel injected into the air are combusted, the combustion gas expands, thereby driving the piston 112 and generating exhaust gas. Then, the exhaust gas from each cylinder 111 is intermittently sent into the exhaust receiver 104.

The fuel supply unit 102 pumps and pressurizes the marine diesel fuel purified by the fuel purifier, and when the fuel valves of the respective cylinders are opened at predetermined timings, the fuel can be injected and supplied into the respective cylinders 111 of the engine main body 101.

The supply air receiver 103 is a compressed air accumulator (scavenging air receiver) for performing a scavenging action of discharging combustion gas in each cylinder 111 of the engine main body 101 and filling with fresh air, and the exhaust air receiver 104 is an exhaust air accumulator capable of accumulating and storing exhaust gas from each cylinder of the engine main body 101 and supplying most of the exhaust gas to the turbocharger 120 side.

The turbocharger 120 has: a turbine 121 driven by the exhaust gas supplied from the exhaust gas receiver 104 side; and a compressor 122 that introduces and compresses external air when driven by the turbine 121, and supplies it into the air supply receiver 103.

The EGR device 130 includes: a wet washing unit 131 that takes in a part of the exhaust gas from the exhaust gas receiver 104 to a recirculation path Le leading to the supply gas receiver 103 side and purifies it; an EGR cooler 132 that cools the exhaust gas (hereinafter referred to as EGR gas) purified by the washing unit 131 by heat exchange; and an EGR blower 133 that boosts the EGR gas cooled by the EGR cooler 132 to a pressure level at which the EGR gas can be supplied from the compressor 122 of the turbocharger 120 into the pressurizing passage Lc leading to the supply air receiver 103.

The wet washing unit 131 includes: a scrubber which, for example, sprays droplets capable of neutralizing sulfur oxides in the exhaust gas introduced into the recirculation path Le, or brings them into a size suitable for absorbing soot particles in the exhaust gas or primary cooling the recirculated exhaust gas in the recirculation path Le; and a mist catcher that collects droplets purified by the returned exhaust gas at an inner bottom side of the scrubber.

Although not shown in detail, the EGR cooler 132 is constituted by a heat exchanger having an EGR gas passage through which the EGR gas that has passed through the washing unit 131 and is purified and primarily cooled, and a cooling water passage through which cooling water from the outside passes, that is, a heat exchanger that can cool (secondary cool) the EGR gas by heat exchange between fluids flowing through both passages.

The EGR blower 133 includes: a housing 10 formed with a gas passage 11 through which EGR gas having passed through the EGR cooler 132 is introduced, and a shaft hole 12 communicating with the gas passage 11; a rotation shaft 21 rotatably inserted into the shaft hole 12 of the housing 10; an impeller 22 supported by the rotation shaft 21 and housed in the casing 10; and a sealing device 30 that seals the shaft hole 12.

As shown in fig. 1, a motor 70 is disposed on the outer surface side (right side in fig. 1) isolated from the gas passage 11 of the housing 10 with respect to the seal case 33, and the motor 70 has an output shaft 71 that drives the rotation shaft 21 to rotate.

As shown in fig. 1 and 2, the gas passage 11 of the housing 10 includes an introduction passage 11a and a scroll passage 11b, the introduction passage 11a is opened at a large diameter on the outer end side of the housing 10, that is, on the left end side in fig. 1, and extends toward the right side (inner side) in the drawing along the axial direction of the rotary shaft 21 and is reduced in diameter on the inner side, and the scroll passage 11b surrounds the inner end portion of the introduction passage 11 a. The housing 10 includes an inlet portion 11c and a blowout port 11d, the inlet portion 11c being opened with a large diameter on the outer end side of the inlet passage 11a, and the blowout port 11d projecting the downstream end of the scroll passage 11b radially outward of the inlet portion 11 c.

The housing 10 is constituted by a main body 13, a motor mounting plate 14, and a plurality of bolts 15, wherein the main body 13 forms the gas passage 11 and is opened on the motor mounting surface side, the motor mounting plate 14 is substantially disk-shaped to block the motor mounting surface side of the main body 13, and a shaft hole 12 is formed in the center portion thereof, and the plurality of bolts 15 detachably fix the motor mounting plate 14 to the main body 13. A mounting bracket 73 for mounting the motor 70 is mounted on the motor mounting plate 14 of the housing 10, and a support bracket 74 for supporting the motor 70 from below is mounted on the rear surface side of the housing 10. The housing 10 is integrally connected to the case 72 of the motor 70 by the mounting bracket 73 and the support bracket 74.

The rotary shaft 21 further includes: a stepped substantially cylindrical body 23 which is a capped cylindrical body connected to the output shaft 71 of the motor 70 so as to be integrally rotatable, and which is fitted to the output shaft 71 of the motor 70 at a predetermined fitting pressure; a cover 24 that is fitted concentrically with one end of the substantially cylindrical body 23 in the impeller 22 and closes the one end; an annular spacer 25 interposed between the cover 24 and the output shaft 71 of the motor 70, capable of positioning the substantially cylindrical body 23 and the cover 24 at a predetermined position in the axial direction with respect to the output shaft 71 of the motor 70; and a bolt 26 that fastens the substantially cylindrical body 23, the cover 24, and the spacer 25 to the output shaft 71 of the motor 70.

The impeller 22 supported by the rotary shaft 21 in the housing 10 includes: an inlet portion 22a in the gas passage 11 adjacent to the inner end portion of the introduction passage 11a, an outlet portion 22b opening in the scroll passage 11b toward the radiation outside direction, and a plurality of vane portions 22c extending from the inlet portion 22a to the outlet portion 22b and separated from each other at equal angular intervals. The impeller 22 constitutes a centrifugal blower together with the casing 10 and the rotary shaft 21, and when driven to rotate by the motor 70 via the rotary shaft 21, pressurizes the EGR gas introduced into the gas passage 11 of the casing 10 so as to be recirculated to the engine 110.

As shown in fig. 2, the sealing device 30 is installed between the housing 10 and the rotary shaft 21, and blocks the gap G around the rotary shaft 21 in the shaft hole 12.

The sealing device 30 is configured to include: an annular first seal ring 31 and a second seal ring 32 surrounding the rotary shaft 21 near one end of the shaft hole 12, and an annular shaft seal case 33 accommodating the first seal ring 31 and the second seal ring 32. As shown in fig. 2 and 3, the seal device 30 includes a static pressure gas seal unit 40 and a backup seal unit 60.

The shaft seal case 33 has an annular wall portion 33a having a circular inner peripheral shape, and a pair of inner side wall portions 33b and 33c, wherein the annular wall portion 33a surrounds the first seal ring 31 and the second seal ring 32, and the pair of inner side wall portions 33b and 33c are integrally coupled to the annular wall portion 33a so as to be substantially orthogonal to the annular wall portion 33a on both sides of the axial direction of the rotary shaft 21.

Specifically, the shaft seal case 33 is constituted by a first annular body 34, a second annular body 35, and a third annular body 36, wherein the first annular body 34 is fixed around the shaft hole 12 of the housing 10 on the outer surface side by a plurality of bolts 33g, the second annular body 35 forms an inner wall portion 33b of one of the pair of inner wall portions, and is fixed to the inner surface side (left end surface side in fig. 2) of the first annular body 34 by the bolts, and the third annular body 36 is integrally formed on the outer surface side of the first annular body 34, and forms an inner wall portion 33c of the other side so as to oppose the inner wall portion 33b of one of the pair of inner wall portions.

The static pressure gas seal unit 40 compresses the plurality of compression coil springs 41 between the first seal ring 31 and the second seal ring 32 provided in the shaft seal case 33 at equal intervals (equiangular intervals) in the circumferential direction, so as to apply force to the first seal ring 31 and the second seal ring 32 to bring them into close contact with the pair of inner side wall portions 33b, 33c of the shaft seal case 33, thereby forming an annular main seal chamber 42 in the shaft seal case 33. The seal air having a pressure higher than that in the gas passage 11 and the shaft hole 12 of the housing 10 is introduced into the main seal chamber 42 from the seal air (seal air) supply circuit 45 shown in fig. 3, and leakage of the exhaust gas from the gas passage 11 in the housing 10 to the atmosphere can be suppressed.

As shown in fig. 3, the seal air supply circuit 45 includes, in an air supply passage 45h communicating with a seal air passage 34h formed in the first annular body 34 of the shaft seal case 33: a check valve 46, a pressure regulating means 47 including a pressure gauge, a flowmeter, a relief valve, a filter, etc., which are not shown, an on-off valve 48, and an air supply source 49 such as an air pump.

For example, by controlling the pressure regulating means 47 and the on-off valve 48 in accordance with the rotation speed [ rpm ], the load, the pressure in the gas passage 11, and the like of the engine 110, the seal air supply circuit 45 can always suppress leakage of the EGR gas from the gas passage 11 in the housing 10 to the atmosphere through the shaft hole 12 by continuously supplying the seal air into the main seal chamber 42 at a supply pressure higher than the pressure of the gap G in the shaft hole 12 communicating with the gas passage 11. Therefore, when the supply pressure of the seal air is always higher than the atmospheric pressure, and the pressure in the gas passage 11 (the pressure on the back surface side of the impeller 22) rises in accordance with any one of the outlet side pressure of the exhaust gas receiver 104 or the back pressure from the turbine 121 side of the turbocharger 120, the inlet side pressure of the supply gas receiver 103 or the boost pressure from the compressor 122 side of the turbocharger 120, the rotation speed [ rpm ] of the motor 70, and the like, the supply pressure of the seal air can be adjusted to be higher than the pressure in the gas passage 11. The supply pressure of the seal air may be increased or decreased stepwise.

The second seal ring 32 on the atmosphere side of the first seal ring 31 and the second seal ring 32 of the static pressure gas seal unit 40 has a split seal structure composed of a plurality of circular arc-shaped split seal members 51 adjacent to each other in the circumferential direction, and a clamp spring 52 that biases the plurality of split seal members 51 toward the rotary shaft 21 side and elastically integrally restricts the plurality of split seal members 51.

In the present embodiment, not only the second seal ring 32 but also the first seal ring 31 that is close to the shaft hole 12 of the housing 10 has a split seal structure including a plurality of circular arc-shaped split seal members 51 that are adjacent in the circumferential direction, and a retainer spring 52 that biases the plurality of split seal members 51 toward the rotary shaft 21 side and elastically integrally restricts the plurality of split seal members 51.

The plurality of segmented seal members 51 of the first seal ring 31 and the second seal ring 32 each have a pair of dowel holes 51k spaced apart by a predetermined angular interval on one surface side, and have a plurality of recessed holding holes 51n capable of holding the ends of the plurality of compression coil springs 41 on the other surface side. The first seal ring 31 and the second seal ring 32 are disposed in opposition to each other such that the concave holding holes 51n and the registration pin holes 51k are open in opposition to each other in the axial direction of the rotary shaft 21.

The plurality of segment seal members 51 are arranged on the same circumference so as to have first opposing faces 51a and second opposing faces 51b, the first opposing faces 51a being expanded in the axial direction and the radial direction and opposing each other with a minute gap Ec therebetween in the circumferential direction, the second opposing faces 51b being expanded in the circumferential direction and the radial direction and opposing each other with a sliding gap Ed therebetween in the axial direction, the plurality of segment seal members 51 being guided to the rotary shaft 21 by the plurality of positioning pins 33j, 33k on the side of the shaft seal case 33 fitted in the plurality of pairs of positioning pin holes 51k, and being pressed against the outer circumferential surface of the rotary shaft 21 with a predetermined contact pressure by the chucking springs 52 on the outer circumferential side.

Here, the minute gap Ec extending in the axial direction of the rotary shaft 21 is not covered by any object on the outer peripheral surface side and the mutually opposite side (concave holding hole 51n side) of the first seal ring 31 and the second seal ring 32, and is narrowed by being covered by the pair of inner wall portions 33b, 33c on the close contact surface side (positioning pin hole 51k side) where the first seal ring 31 and the second seal ring 32 are in close contact with the pair of inner wall portions 33b, 33 c.

Further, on both axial surfaces of the first seal ring 31 and the second seal ring 32, the minute gaps Ec extending in the axial direction of the rotary shaft 21 are shifted in position in the circumferential direction, and as shown in fig. 4B, the sliding gaps Ed extending in the circumferential direction are curved in opposite directions between the minute gaps Ec on both axial surfaces of the first seal ring 31 and the second seal ring 32 and are narrower than the minute gaps Ec on both axial surfaces. These minute gaps Ec and Ec constitute small hole-shaped leakage passages 51e with large pressure loss.

The backup seal unit 60 has: a ring-shaped third seal ring 61 which is disposed on the outer surface side (right end side in fig. 2) of the shaft seal case 33 isolated from the gas passage 11 of the housing 10, and which surrounds the rotary shaft 21; an outer annular member 63 provided to cover the third seal ring 61 from the radially outer side and the axially outer side and detachably fixed to the first annular body 34 of the seal case 33 by bolts 66; an elastic member 64 such as a compression coil spring that biases the third seal ring 61 in close contact with the inner wall 63a of the outer annular member 63 outward in the axial direction of the rotary shaft 21; and an airtight seal 65 which is installed between the first annular body 34 and the outer annular member 63 of the shaft seal case 33 and is constituted by a rubber elastic ring.

The backup seal unit 60 forms an auxiliary seal chamber 62 between the seal case 33 and the outer annular member 63, which restricts leakage of seal air from the main seal chamber 42 of the static pressure gas seal unit 40 to the atmosphere.

Although not shown in detail, the third seal ring 61 of the backup seal unit 60 has a split seal structure including a plurality of circular arc-shaped split seal members (corresponding to the split seal members 51) adjacent to each other in the circumferential direction, and a clamp spring (corresponding to the clamp spring 52) that biases the plurality of split seal members toward the rotary shaft 21 side and elastically integrally restricts the plurality of split seal members, substantially the same as the second seal ring 32 on the atmosphere side of the static pressure gas seal unit 40.

The plurality of segment sealing members of the third seal ring 61 also have small hole-shaped leakage paths (indicated by a bracket 61e in the figure) having a large pressure loss due to the plurality of segment sealing members, like the plurality of arc-shaped segment sealing members 51 of the second seal ring 32 shown in fig. 4A and 4B.

In the sealing device 30 of the present embodiment, when the supply pressure of the seal air supplied to the main seal chamber 42 is a pressure p1[ MPa ] sufficiently higher than the atmospheric pressure, the condition that the seal air leaking from the leakage passage 51e of the second seal ring 32 becomes a so-called choked flow (choked flow) (p2+0.1)/(p1+0.1) can be satisfied that the critical pressure ratio b or lower. In this case, when the seal air leaks from the main seal chamber 42 to the auxiliary seal chamber 62 side, a large pressure loss corresponding to the upstream pressure P1 occurs due to the second seal ring 32, effectively restricting the mass flow rate of the seal air leaking from the main seal chamber 42 to the auxiliary seal chamber 62 side.

In this case, the pressure P2 in the auxiliary seal chamber 62 is equal to or higher than the atmospheric pressure but equal to or lower than the predetermined pressure which is sufficiently lower than the pressure P1 of the seal air in the main seal chamber 42, and the atmospheric pressure P3 MPa which is the downstream pressure is larger than the pressure P2 in the auxiliary seal chamber 62 which is the upstream pressure of the third seal ring 61. Thus, the condition that the seal air leaking from the small hole-shaped leakage passage 61e of the third seal ring 61 is a so-called subsonic flow ((p3+0.1)/(p2+0.1) is greater than the critical pressure ratio b) is established. Therefore, the mass flow rate of the seal air leaking from the auxiliary seal chamber 62 to the atmosphere side depends on both the pressure P2 in the auxiliary seal chamber 62 and the atmospheric pressure P3, and is sufficiently restricted by the third seal ring 61 (the flow rate in the auxiliary seal chamber 62 is smaller than that in the case where the flow becomes blocked at a high pressure of about the pressure P1).

On the other hand, when the supply pressure of the seal air supplied to the main seal chamber 42 is higher than the atmospheric pressure but not so high, or when the supply pressure of the seal air supplied to the main seal chamber 42 is a pressure P1 sufficiently higher than the atmospheric pressure but the pressure P2 in the auxiliary seal chamber 62 is high, the condition ((p2+0.1)/(p1+0.1) is higher than the critical pressure ratio b) that the seal air leaking from the small hole-shaped leakage passage 51e of the second seal ring 32 becomes subsonic flow is satisfied.

In this case, the mass flow rate of the seal air leaking from the main seal chamber 42 to the auxiliary seal chamber 62 side depends on both the pressure P1 in the main seal chamber 42 and the pressure P2 in the auxiliary seal chamber 62, and is sufficiently restricted by the second seal ring 32 (flow rate smaller than that in the case of blocking flow).

In this way, the EGR blower 133 having the seal device 30 of the present embodiment sufficiently reduces the leakage amount of the seal air leaking out to the atmosphere through the shaft hole 12 of the housing 10 by making the static pressure gas seal unit 40 and the backup seal unit 60 of the seal device 30 cooperate.

As shown in fig. 2, a circular ring-shaped drop plate 81 having a diameter larger than the inner diameter of the outer annular member 63 is disposed on the rotary shaft 21 located axially outside the outer annular member 63 with respect to the housing 10. The drop plate 81 protrudes in a substantially perpendicular baffle-like manner from the outer peripheral surface of the rotary shaft 21, and drops the seal air leaking from the auxiliary seal chamber 62 in the axial direction of the rotary shaft 21 together with surrounding dust and the like in the radiation outward direction, thereby suppressing intrusion of dust into the motor 70 side.

However, in the turbocharger 120, when the turbine 121 is driven to rotate by the exhaust energy from the exhaust gas receiver 104 of the engine 110, the fresh air (air from the outside) and the EGR gas that are drawn into the compressor 122 are pressurized, and are boosted to the supply gas receiver 103 side of the engine 110 at a predetermined boost pressure. The turbocharger 120 may be configured to control the intake of exhaust gas into the turbine 121 by a variable nozzle function or bypass exhaust gas and control the bypass flow rate thereof according to a preset operation condition. In this case, the energy of the exhaust gas from the exhaust gas receiver 104 may be changed according to the operating state of the engine 110, and the boost pressure of the turbocharger 120 may be appropriately controlled.

In addition, the EGR apparatus 130 can selectively limit the operation thereof by narrowing or blocking the recirculation path Le according to the rotation speed [ rpm ] of the engine or according to a preset operation condition. In this way, the emission of NOx can be selectively limited according to the rotation speed [ rpm ] of the engine or the sailing sea area of the ship.

Next, the operation will be described.

In the EGR blower 133 provided with the sealing device 30 of the present embodiment having the above-described configuration, the seal air having a pressure higher than the pressure in the shaft hole 12 communicating with the gas passage 11 is introduced into the main seal chamber 42 formed between the first seal ring 31 and the second seal ring 32 by the static pressure gas seal means 40, so that the exhaust gas in the EGR blower 133 can be reliably prevented from leaking from the gas passage 11 side to the atmosphere side.

Further, since the front-rear pressure difference of the second seal ring 32 is suppressed by the third seal ring 61 of the backup seal unit 60 and the front-rear pressure difference of the third seal ring 61 is also suppressed, the leakage flow rate of the seal air to the atmosphere, which can be changed in accordance with the front-rear pressure differences of the seal rings 32, 61, can be further effectively suppressed by the cooperation of the static pressure gas seal unit 40 and the backup seal unit 60.

In the present embodiment, the blower is configured such that a gas passage 11 through which a part of the exhaust gas of the engine 110 can be introduced is formed in the housing 10, the rotary shaft 21 is inserted into the shaft hole 12 communicating with the gas passage 11 to support the impeller 22, and the exhaust gas introduced into the gas passage 11 is boosted to be recirculated to the engine 110, so that the blower is applied to the EGR blower 133 capable of recirculating the exhaust gas of the engine 110 to reduce the amount of NOx and the like.

In the present embodiment, at least the second seal ring 32 on the atmosphere side of the first seal ring 31 and the second seal ring 32 is constituted by the plurality of arcuate segment seal members 51, and therefore, the minute gaps Ec and Ed between the plurality of segment seal members 51 can be set to an appropriate shape and size according to the inner peripheral surface shape and end shape, and the leakage flow rate of the seal air passing through the minute gaps of the second seal ring 32 and the front-rear pressure difference of the second seal ring 32 can be ensured stably.

In the present embodiment, the backup seal unit 60 has the outer annular member 63 covering the third seal ring 61 from the radially outer side and the axially outer side, and the elastic member 64 biasing the third seal ring 61 in the axial direction of the rotary shaft 21 so as to bring the third seal ring 61 into close contact with the outer annular member 63, and therefore, the auxiliary seal chamber 62 can be easily formed by the third seal ring 61 and the outer annular member 63, and the stable seal posture of the third seal ring 61 can be set, so that leakage of seal air to the atmosphere during operation can be more effectively reduced.

In the present embodiment, the outer annular member 63 is detachably coupled to the shaft seal case 33 on the outer side in the axial direction of the shaft seal case 33 with respect to the gas passage 11, and therefore the third seal ring 61 and the outer annular member 63 can be easily added to a conventional blower.

In the preferred embodiment of the present invention, the motor 70 for driving the rotation shaft 21 to rotate is disposed on the outer side in the axial direction of the shaft seal case 33 isolated from the gas passage 11, and the housing 10 is integrally connected to the case 72 of the motor 70, so that the compact EGR blower 133 can be manufactured.

In the present embodiment, since the annular plate-like drop plate 81 having a diameter larger than the inner peripheral diameter of the outer annular member 63 (the aperture (2R 1) corresponding to the radius R1 in fig. 2) is disposed on the rotating shaft 21 on the outer side in the axial direction than the outer annular member 63, the seal air leaking out of the auxiliary seal chamber 62 to the outer side in the axial direction can be dropped in the radiation outside direction together with the surrounding dust and the like by the drop plate 81, and intrusion of dust into the motor 70 side can be effectively suppressed.

As described above, in the present embodiment, the mechanical seal type sealing device 30 for blocking the shaft hole 12 of the EGR blower 133 is configured to include: a first seal ring 31 and a second seal ring 32 which surround the rotary shaft 21 in the vicinity of the shaft hole 12; an annular shaft seal case 33 having an annular wall portion 33a surrounding the first seal ring 31 and the second seal ring 32, and a pair of inner wall portions 33b, 33c integrally joined to the annular wall portion 33a on both sides in the axial direction of the rotary shaft 21; a static pressure gas seal unit 40 in which a main seal chamber 42 is formed in the shaft seal case 33 to prevent leakage of exhaust gas from the gas passage 11 to the atmosphere, the main seal chamber 42 being configured to introduce seal air having a pressure higher than that in the gas passage 11 and to bring the first seal ring 31 and the second seal ring 32 into close contact with the pair of inner side wall portions 33b, 33c; and a backup seal unit 60 having an annular third seal ring 61 and forming an auxiliary seal chamber 62 that restricts leakage of seal air from the main seal chamber 42 to the atmosphere, the third seal ring 61 surrounding the rotary shaft 21 on the outside in the axial direction that is isolated from the gas passage 11 with respect to the seal case 33.

Accordingly, leakage of exhaust gas in the EGR blower 133 from the gas passage 11 side to the atmosphere side in the ship can be effectively suppressed by the pressurized seal air of the static pressure gas seal unit 40, and the leakage amount of seal air to the atmosphere side can be sufficiently reduced by the cooperation of the static pressure gas seal unit 40 and the backup seal unit 60.

In the EGR blower 133 according to the above embodiment, the rotary shaft 21 is fastened to the output shaft 71 of the motor 70, but as shown in fig. 5, the EGR blower may be configured to include a seal-dedicated rotary sleeve 27 fixed to the outer peripheral surface of the substantially cylindrical body 23 in a rotationally fixed manner, in addition to the substantially cylindrical body 23 of the rotary shaft 21 fastened to the output shaft 71 of the motor 70, and the rotary sleeve 27 may be provided with a surface treatment portion 27a, and the surface treatment portion 27a may form a sliding surface having a small frictional resistance against sliding of the seal rings 31, 32, 61 and excellent wear resistance.

In the above-described embodiment, the seal rings 31, 32, 61 each have the same split seal structure, but it is obvious that the first seal ring 31 or the third seal ring 61 may have a seal structure different from that of the second seal ring 32. In addition, although the engine 110 is used for a ship in one embodiment, the present invention is also applicable to a large engine other than a ship, for example, a case where a stationary engine or the like for operating a generator is provided in a relatively narrow space.

As described above, the present invention can provide a blower capable of suppressing power consumption of a seal air supply source, and can provide a blower suitable for an EGR blower of a marine engine, and can be applied to all blowers of an exhaust gas recirculation system of a large engine.

Reference numerals illustrate:

10. Outer casing

11. Gas channel

12. Shaft hole

21. Rotary shaft

22. Impeller wheel

30. Sealing device

31. First sealing ring

32. Second sealing ring

33. Shaft seal box

33A annular wall portion

33B, 33c of a pair of inner side wall portions

34H seal air passage

40. Static pressure gas sealing unit

42. Main seal chamber

45. Sealed air supply circuit

51. Segmented seal component

51A first opposing face

51B second opposite face

51E, 61e leakage path

60. Standby sealing unit

61. Third sealing ring

62. Auxiliary sealing chamber

63. Outer ring-shaped member

63A inner sidewall portion

64. Elastic component

65. Hermetic seal

70. Motor with a motor housing having a motor housing with a motor housing

71. Output shaft

81. Throwing plate

100. Power system

103. Air supply receiver

104. Exhaust gas receiver

110. Engine with a motor

120. Turbocharger with a variable-speed control valve

130 EGR device

133 EGR blower

Ec micro gap

Ed sliding gap

Lc boost passage

Le recirculation path

P1 pressure (pressure in main seal chamber)

P2 pressure (pressure in auxiliary seal chamber)

P3 atmospheric pressure.

Claims

1. A blower is provided with:

a housing having a gas passage through which a part of exhaust gas of an engine can be introduced and a shaft hole communicating with the gas passage;

a rotation shaft rotatably inserted into the shaft hole of the housing;

An impeller supported by the rotary shaft and housed in the casing, the impeller recirculating the exhaust gas introduced into the gas passage and boosted to the engine; and

A sealing device for sealing the shaft hole,

The blower is characterized in that,

The sealing device comprises:

A first seal ring and a second seal ring in the form of rings surrounding the rotary shaft in the vicinity of the shaft hole;

an annular shaft seal case having an annular wall portion surrounding the first seal ring and the second seal ring, and a pair of inner wall portions integrally joined to the annular wall portion on both sides in an axial direction of the rotary shaft;

A static pressure gas seal unit that forms a main seal chamber in the shaft seal case so as to prevent leakage of the exhaust gas from the gas passage to the atmosphere, the main seal chamber being introduced with seal air and bringing the first seal ring and the second seal ring into close contact with the pair of inner side wall portions;

A backup seal unit having an annular third seal ring that surrounds the rotary shaft on an axially outer side of the seal box from the gas passage, and forming an auxiliary seal chamber that restricts leakage of seal air from the main seal chamber to an atmosphere side; and

A seal air supply circuit that supplies the seal air to the static pressure gas seal unit at a supply pressure higher than the atmospheric pressure and higher than the pressure in the gas passage, and increases or decreases the supply pressure according to a pressure change in the gas passage,

And limiting the leakage flow of the sealing air from the main sealing chamber to the atmosphere side through the seal ring on the atmosphere side in the first seal ring and the second seal ring of the static pressure gas seal unit and the standby seal unit.

2. A blower according to claim 1, wherein the blower is configured to,

The engine is a multi-cylinder diesel engine mounted as a main engine in a cabin of a ship.

3. A blower according to claim 1 or 2, wherein,

The second seal ring and the third seal ring on at least the atmosphere side of the first seal ring and the second seal ring are each composed of a plurality of arc-shaped segment seal members adjacent to each other in the circumferential direction, and a retainer spring that biases the plurality of segment seal members toward the rotating shaft side and elastically integrally retains the plurality of segment seal members,

The plurality of segmented seal members have first and second opposing faces with each other, the first opposing face expanding in an axial direction and a radial direction and opposing in a circumferential direction, and the second opposing face expanding in the circumferential direction and the radial direction and opposing in the axial direction.

4. A blower according to claim 1 or 2, wherein,

The backup seal unit further includes an outer annular member that covers the third seal ring from a radially outer side and an axially outer side with respect to an axial outer side of the shaft seal case that is isolated from the gas passage, and an elastic member that biases the third seal ring in an axial direction of the rotary shaft so as to bring the third seal ring into close contact with the outer annular member.

5. A blower according to claim 4, wherein the blower is configured to,

The outer annular member is fixed axially outward of the shaft seal case from the gas passage.

6. A blower according to claim 5, wherein the blower is configured to,

The blower is provided with a motor for driving the rotation shaft to rotate,

The housing is integrally connected with the motor.

7. The blower of claim 6, wherein the blower is configured to control the blower,

An annular plate-shaped drop plate having a diameter larger than the inner peripheral diameter of the outer annular member is disposed on the rotating shaft on the outer side in the axial direction than the outer annular member.

8. A sealing device for a blower, the sealing device for a blower being attached to the blower and sealing a shaft hole, the blower comprising:

A housing having a gas passage through which a part of exhaust gas of an engine can be introduced and the shaft hole communicating with the gas passage;

a rotation shaft rotatably inserted into the shaft hole of the housing; and

An impeller which is supported by the rotary shaft and housed in the casing, and which recirculates the exhaust gas introduced into the gas passage and boosted to the engine,

The sealing device of the blower is characterized by comprising: